Abstract : Research on 2-dimensional static articulatory modeling has been performed by using the semi-polar system and the guided PCA analysis of lateral X-ray images of vocal tract. The density of the grid lines in the semi-polar system has been increased to have a better descriptive precision. New parameters have been introduced to describe the movements of tongue apex. An extra feature, the tongue root, has been extracted as one of the elementary factors in order to improve the precision of tongue model. New methods still remain to be developed for describing the movements of tongue apex.